Internally mounted fuel manifold with support pins

ABSTRACT

A method and apparatus for internally mounting a fuel manifold within a surrounding casing in a gas turbine engine which involves inserting the fuel manifold into the casing with support elements positioned in a retracted position, displacing the support elements into an extended position, and fastening said support elements to mount the manifold to an inner surface of said casing.

TECHNICAL FIELD

The invention relates generally to fuel manifolds for gas turbineengines and, more particularly, to an improved structure and method formounting fuel manifolds.

BACKGROUND OF THE ART

Annular fuel manifolds which distribute fuel to a plurality of fuelnozzles for injection into the combustion chamber of a gas turbineengine are typically supported within the surrounding structure of theengine by several radially extending support pins which are externallymounted and inserted through the engine casing for engagement with thefuel manifold. As such, the circumferentially spaced pins support theannular fuel manifold within the surrounding casing such that the fuelmanifold is located in place adjacent a dome end of the combustor whilenevertheless permitting sufficient displacement to accommodate anythermal growth mismatch between the fuel manifold and the supportingcasing.

However such support pins are assembled from the outside of the enginecasing and therefore assembly and installation of the pins to mount thefuel manifold in place can be time consuming and problematic due toobstruction by other engine components which surround the combustionsection of the gas turbine engine. Removal and re-installation of thefuel manifold for inspection and/or maintenance purposes thus alsobecomes problematic.

Accordingly, there is a need to provide an improved method and structureto assemble and mount a fuel manifold using support pins.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide an improvedstructure and method for mounting fuel manifolds.

In one aspect, the present invention provides a method of installing afuel manifold within a casing of a gas turbine engine comprising:providing the fuel manifold with attachment members fixed thereto, eachof said attachment members defining an aperture for receiving a supportelement therein; mounting said support elements on said fuel manifold ina retracted position within said apertures such that said supportelements project a first distance from said fuel manifold, said fuelmanifold and said support elements mounted thereto in said retractedposition forming a sub-assembly sized for receipt within said casing;inserting said sub-assembly into said casing; displacing said supportelements outwards from retracted position into an extended positionwherein the support elements project from the fuel manifold as seconddistance greater than said first distance, outer ends of said supportelements being disposed proximate an inner surface of said surroundingcasing when said support elements are disposed in said extendedposition; and fastening said outer ends of said support elements to saidinner surface of said casing.

In another aspect, the present invention provides a method of internallymounting a fuel manifold within a surrounding casing in a gas turbineengine, the gas turbine engine including support elements mounted to atleast one of the fuel manifold and the surrounding casing and movablerelative thereto between at least a retracted and an extended positionwhile mounted thereto, the method comprising: placing the supportelements mounted in a retracted position; inserting the fuel manifoldinto the casing; and moving said support elements to the extendedposition to supportingly engage said fuel manifold to said casing.

In yet another aspect, the present invention provides a fuel manifoldassembly for internal mounting within a surrounding casing of a gasturbine engine, comprising: an annular fuel manifold having mountingportions spaced about the circumference thereof; support pins engageablewith said mounting portions and displaceable relative thereto between aretracted position, permitting said fuel manifold and said support pinsto be inserted within the casing, and an extended position, in whichsaid support pins project outwardly from said fuel manifold forengagement with said casing; and wherein said support pins aredisplaceable from said retracted position to said extended position onceinserted into said casing for fastening to an inner surface thereof.

Further details of these and other aspects of the present invention willbe apparent from the detailed description and figures included below.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures depicting aspects ofthe present invention, in which:

FIG. 1 is a partial cross-sectional view of a gas turbine engine;

FIG. 2 is a partial schematic cross-sectional view of an annular fuelmanifold internally mounted within the gas generator case by support pinassemblies according to the present invention; and

FIG. 3 is a perspective view of the annular fuel manifold and a supportpin assembly of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, amultistage compressor 14 for pressurizing the air, a combustor 16defining a combustion chamber 17 within which the compressed air ismixed with fuel and ignited for generating an annular stream of hotcombustion gases, and a turbine section 18 for extracting energy fromthe combustion gases.

Fuel is injected into the combustor 16 using a fuel injection system 20,which comprises a fuel manifold ring 22 disposed outside the combustor16 and n internally mounted within the surrounding engine casing.

Referring to FIGS. 2 and 3, the annular fuel manifold 22 is internallymounted within the gas generator casing 26 of the engine, adjacent to anupstream or dome end 19 of the combustor 16. The fuel manifold 22 has amain ring body 23 defining at least one fuel flow passage 25 therein andpreferably also includes an outer heat shield 27 which at leastpartially encloses the main ring body 23. The fuel passage 25 of theannular fuel manifold ring 22 is disposed in fuel flow communicationwith a plurality of fuel injector spray tip assemblies (not shown),which typically project from the fuel manifold into the combustionchamber 17 for injecting fuel and combustion air therein. The fuelmanifold 22 includes mounting portions disposed at several pointsthereabout for mounting the fuel manifold within the surrounding casing26. The mounting portions are preferably in the form of attachment lugs24, which are fixed to the main ring body 23 and project, preferablyaxially, therefrom such as to permit a support element 30 to bedisplaced therethrough without contacting or fouling on the main ringbody 32 of the manifold. The main ring body 23 may also be provided witha recess formed therein in alignment with each attachment lug 24, suchthat the support element may slide within the lugs as described in moredetail below without contacting the main ring body. The surrounding heatshield 27 also preferably includes recesses 33 therein, such thatdisplacement of the support elements 30 remains uninhibited. Therecesses 33 in the heat shield 27 are circumferentially aligned witheach of the attachment lugs 24. The attachment lugs 24 may be eitherpermanently fastened to the main ring body 23, or alternately may beintegrally formed therewith. Each attachment lug 24 define at least oneaperture 32 therein for receiving a support element 30 which isfastenable to the gas generator case 26 in order to internally mount thefuel manifold 22 therewithin. The gas generator case 26 is preferably anannular casing defining circumferential inner and outer surfaces 38 and39 respectively.

The support elements preferably comprise support pins 30, which areslidably displaceable within the apertures 32 of the attachment lugs 24,preferably along a center axis of the apertures 32 which is coaxial withthe longitudinal axis 42 of the support pins 30, between at least aninner or retracted position (depicted in FIG. 2 with dotted lines 34)and an outer or extended position (depicted in FIG. 2 with solid lines).When disposed in said retracted position, the fuel manifold with saidsupport pins 30 mounted thereto defines an overall diameter which issufficiently small to fit within an inner clearance diameter definedbetween the inner surfaces 39 of the surrounding gas generator casing26. Thus, the installation and internal mounting of the fuel manifoldwithin the casing is possible without having to insert the support pinsfrom the outside of the casing, as the sub-assembly formed by theannular fuel manifold 22 and the support pins 30 mounted therein in saidretracted position, can be inserted directly into the casing forinternal mounting therewithin.

Each support pin 30, which includes a radially inner end 31 and aradially outer end 36, therefore radially projects a first distance awayfrom the attachment lugs 24 (and therefore the fuel manifold 22) whendisposed in the retracted position and projects a second distance,greater than the first distance, when disposed in the extended position.This accordingly permits a sub-assembly formed by the fuel nozzle andthe support pins 30 mounted thereon in the retracted position, to beinserted within the case together. Once located within the casing 26,the support pins 30 can be slid radially outward along theirlongitudinal axes 42 (i.e. towards the inner surface of the casing) fromtheir retracted position to their extended position, such that the outerends 36 of the pins 30 can be fastened to the casing 26 from the innerside thereof. More particularly, the casing 26 preferably includesattachment bosses 28 disposed therein at points which correspond to theattachment lugs 24 of the fuel manifold, and which have threadedapertures 40 therethrough. The outer ends 36 of the support pins 30 arecorrespondingly threaded, such that the pins 30 can be threadablyfastened within the apertures 40 of each of the bosses 28 in the casing26. Thus, so fastened to the surrounding casing 26, the support pinsradially project inwards towards the engine centerline 11, in order toretain the annular fuel manifold 22 in place therewithin. Once mountedin place, some radial displacement between the fuel manifold 22 and thesupport pins 30 remains possible due to the sliding link between theapertures 32 in the attachment lugs 24 and the inner ends 31 of the pins30. Thus, any relative thermal growth between the fuel manifold and thesupport pins and casing can be accommodated.

Preferably, the pins 30 are translated outward along their longitudinalaxis 42 between the retracted and the extended positions. In order toslide the pins 30 outwardly into the extended positions, an appropriatetool is preferably inserted through the apertures 40 and used to pullthe outer ends 36 of the pins 30 outwards from the outer side of thecasing 26. The pins 30 can then be rotated in place about theirlongitudinal axis 42, in order to threadably fasten them within thebosses 28. Wrenching flats 44 may be provided on the body of the supportpins 30 in order to permit the pins to be rotated by a suitable toolsuch as a torque wrench and torqued into place within threaded apertures40. A washer 48 is disposed about each support pin 30, and is adapted tobe squeezed between the projecting portion 43 of the pin 30 having thewrenching flats 44 thereon and the mating inner surface 29 on the casingbosses 28.

When the annular fuel manifold 22 is inserted into the casing 26, thisis preferably done by aligning the center of the annular manifold with amain longitudinal axis of the casing 26, which in the present casecorresponds to the centerline axis 11 of the gas turbine engine 10. Thefuel manifold 22 is then displaced coaxially along this longitudinalcenter axis until the fuel manifold is located in a predeterminedfore-aft position within the casing 26, particularly adjacent the domeend 19 of the combustor 16. The support pins 30 can then be radiallyoutwardly displaced into their extended positions, as described above,for fastening within the casing 26.

Thus, as the fuel manifold 22 is able to be installed and/or removedfrom the gas generator casing 26 of the gas turbine engine 10 from theinner side thereof, this enables the fuel manifold to be installed orremoved from the casing, and therefore from the engine, regardless ofany radially external obstructions which may be installed about theoutside the casing. For example, once the bypass air duct is installedoutside the gas generator casing 26 surrounding the combustor 16,removal or installation of the fuel manifold 22 remains possible due tothe internal mounting configuration thereof. This was previously notpossible with externally mounted fuel manifolds of the prior art, whichnecessitated accessing the supporting pins from the outside of the gasgenerator casing, and therefore required complete removal of the bypassduct in order to do so.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without department from the scope of the invention disclosed.For example, although an annular fuel manifold is described anddepicted, a non-annular fuel manifold may also be used. Further,although a number of support pins are preferably provided and equallydistributed about the circumference of the fuel manifold, groupings of anumber of support pins may also be used, and the distribution of supportpins about the fuel nozzle may be unevenly distributed in order toprovide additional support to areas predetermined to require additionalsupport and localization within the surrounding gas generator case.Further still, although the support pins are preferably displacedlinearly or translated by sliding between their retracted positions andtheir extended positions, the pins may be alternately displaced betweenthe two positions. For example, the support pins may be hinge orotherwise interconnect with the fuel manifold, and simply pivoted orrotated from retracted position to the extended position. Althoughsupport pins have been described as “pins”, they need not be pins, perse, but rather any suitable support arrangement extending betweenmanifold and surrounding structure. The manifold supports need notengage the gas turbine case directly. While the embodiments describedabove generally contemplate supports mounted to the manifold and whichextend outwardly to engage the engine case surrounding supportstructure, the present invention also encompasses an inversearrangement, wherein supports are mounted to the engine case or othersupport structure, retract generally outwardly and extend generallyinwardly for engagement with the manifold. Still other modificationswhich fall within the scope of the present invention will be apparent tothose skilled in the art, in light of a review of this disclosure, andsuch modifications are intended to fall within the appended claims.

1. A method of installing a fuel manifold within a casing of a gasturbine engine comprising: providing the fuel manifold with attachmentmembers fixed thereto, each of said attachment members defining anaperture for receiving a support element therein; mounting said supportelements on said fuel manifold in a retracted position within saidapertures such that said support elements project a first distance fromsaid fuel manifold, said fuel manifold and said support elements mountedthereto in said retracted position forming a sub-assembly sized forreceipt within said casing; inserting said sub-assembly into saidcasing; displacing said support elements outwards from the retractedposition into an extended position wherein the support elements projectfrom the fuel manifold a second distance greater than said firstdistance, outer ends of said support elements being disposed proximatean inner surface of said surrounding casing when said support elementsare disposed in said extended position; and fastening said outer ends ofsaid support elements to said inner surface of said casing.
 2. Themethod as defined in claim 1, wherein said fuel manifold is annular andsaid attachment members are circumferentially spaced about said fuelmanifold, the step of displacing said support elements furthercomprising sliding said support elements radially outwards from saidattachment members.
 3. The method as defined in claim 2, wherein thecasing is annular and defines a longitudinal center axis therethrough,the step of inserting further comprising aligning a center of saidannular fuel manifold with said longitudinal center axis and displacingsaid sub-assembly co-axially along said longitudinal center axis.
 4. Themethod as defined in claim 1, wherein the step of fastening furthercomprises threadably fastening said outer ends of said support elementswith corresponding threaded openings defined in said casing.
 5. Themethod as defined in claim 1, wherein the support elements are elongatedand define longitudinal axes therethrough, the step of displacingfurther comprising translating said support elements relative to saidattachment members along said longitudinal axes thereof.
 6. The methodas defined in claim 5, wherein the support elements are translatedoutwards along said longitudinal axes by pulling said support elementsfrom outside said casing via openings defined therein.
 7. A method ofinternally mounting a fuel manifold within a surrounding casing in a gasturbine engine, the gas turbine engine including support elementsmounted to at least one of the fuel manifold and the surrounding casingand movable relative thereto between at least a retracted and anextended position while mounted thereto, the method comprising: placingthe support elements mounted in a retracted position; inserting the fuelmanifold into the casing; and moving said support elements to theextended position to supportingly engage said fuel manifold to saidcasing by manipulating said support elements from outside said casingvia openings defined in said casing.
 8. The method as defined in claim7, with said support elements are mounted to the fuel manifold, andwherein the extended position is radially outward the retracted positionrelative to the manifold.
 9. The method as defined in claim 7, whereinthe step of moving said support elements further comprises radiallytranslating said support elements.
 10. The method as defined in claim 7,wherein the step of inserting said fuel manifold into said casingfurther comprises axially translating said fuel manifold along a centrallongitudinal axis of said casing.